Evaporator construction



Nov. 16, 1954 w. R. WILLIAMSON 2,694,676

EVAPORATOR CONSTRUCTION Filed 001;. '7, 1950 William R. Williamsen Inventor Afforn ey Patent Ofiice 2,694,676 Patented Nov. 16, 1954 EVAPORATOR CONSTRUCTION William R. Williamson, Hartford, Conn., assignor to The Maxim Silencer Company, Hartford, (10:111., a corporation of Connecticut Application October 7, 1950, Serial No. 188,983

4 Claims. (Cl. 202235) This invention relates to improvements in the construction of evaporators specifically intended for producing drinking water from sea water by distillation. The great difficulty with such evaporators is the formation of scale, which must be removed periodically from the evaporator walls (as by a shocking process consisting in changing pressure conditions rapidly to cause flexing of the walls to crack off the scale). It is also necessary to withdraw water from the boiler either continuously or from time to time to prevent undue concentration of dissolved salts. Difliculty has hitherto been experienced in clogging of the drain-off pipes by accumulations of scale. It is one object of the invention to prevent clogging of the drain pipes by removing scale automatically from the pipe openings as it is loosened from the walls of the evaporator.

The invention will now be described with reference to the accompanying drawings, in which Fig. 1 is a side elevation, partly broken away in median section;

Fig. 2 is a detail of a screen; and

Fig. 3 is a section on line 33 of Fig. 1.

The evaporator is mounted on a hollow base 1 closed off at the bottom by a plate 2 and at the top by an annular plate 3. A steam inlet pipe 4 enters the base at one side and turns upwardly so as to extend at 5 some distance above the upper plate 3. The extension 5 is somewhat smaller than the hole in plate 3 so that an annular drainage space 6 is provided. A sleeve 7 is secured to the annular plate adiacent its hole, and is secured at its upper end to a basket constructed as in the prior application of Tyskewicz and Williamson Ser. No. 90,528, filed April 29, 1949. The details of this gasket need not be gone into here except to say that it has a side wall 8 formed with deep corrugations 9 which are sealed at their upper and lower ends. A plate 10 closes the space within the series of corrugations at the top, and the inner portions of the corrugations are sealed at the bottom to the sleeve 7. The basket lies within an evaporator chamber 11 formed by a shell 12, the plate 3 and an apertured plate 13. Above the evaporator chamber the shell is closed at its top by a header 14 to form a chamber divided by a baffie 15 into a lower constant level water supply chamber 16 and a separating chamber 17. It will be seen that the basket forms a container with a deeply corrugated side Wall 8 and with a downwardly extending neck formed by the sleeve 7 which is secured ti htly to the lower plate 3 of the evaporator chamber. The steam inlet pipe 4, 5 delivers steam to the interior of this container and through the side wall 8 heats the sea water in the evaporator chamber 11 surrounding it. In this process the heating steam gives up heat and is condensed within the container. the water of condensation passing downwardly through the annular drainage space 6 to be removed therefrom by a pipe 28.

As described in said prior application. sea water is led to chamber 16 through a float controlled valve 18 so that a predetermined minimum water level is maintained. A pipe 19 leads from the constant-level chamber 16 to a point below the water level in the evaporator chamber 11. A vapor pipe 20 leads from the evaporator chamber through the constant level chamber and outside the shell, and then upwardly to the upper portion of the separator chamber which it enters tangentially. The vapor pipe 20 contains a throttle valve 21 which controls the purity of the distillate in the manner described in the patent to Williamson 2,392,893, Jan. 15, 1946. The vapor separated from entrained water in the separator chamber passes through a side entrance 22 in a pipe 23 leading to a suitable condenser.

The sea water in the evaporator chamber 11 gradually deposits scale on the walls of the chamber and basket, and gradually becomes more concentrated, so that it is necessary to bleed oif a portion through a pipe 24. A second pipe 25 is provided for drainage purposes. These pipes pass through the annular plate 3 and are preferably flush with its outer surface at points spaced inwardly from its periphery. In the past the drain pipes from the evaporator chamber have given considerable trouble by becoming clogged with scale, and attempts to strain out the scale resulted in even Worse clogging. In the present case a conical screen 26 is located between the top of the sleeve or neck 7 and the outer edge of the annular plate 3. The strainer is preferably not fastened in place but is loose so that it can be rotated to bring its entire surface successively adjacent a hand hole 27. Any scale which flakes off from the walls of the evaporator chamber or basket will slide down the slanting surface of the screen into the corner adjacent the shell 12. The surface of the screen is very large relative to the size of the drain pipes, and a relatively great quantity of scale can be accommodated in the corner mentioned before cleaning is necessary. Further, by spacing the drain pipes from the corner the accumulation of scale is always remote from the entrance to the pipes.

What I claim is:

1. In combination with an evaporator having an evaporator chamber, heat transfer means within the chamber comprising a container provided with a neck at the bottom passing through the bottom wall of the chamber in fluid tight relation thereto, said means defining means for the removal of condensate from the container, steam supply means extending through said neck and opening into said container, and a drain for said chamber located between its outer wall and said neck; a screen rotatably positioned in the chamber in the form of a frustum of a cone extending between said outer wall of the chamber and said neck and overlying said drain.

2. A device according to claim 1 in which the screen is in the form of a frustum of a cone with its largest diameter at the bottom.

3. A device according to claim 1 in which the steam supply includes a pipe passing within the neck of the container and spaced therefrom to further define the condensate removal means as annular.

4. In combination with an evaporator having an evap orator chamber, heat transfer means within the chamber comprising a container provided with a neck at the bottom passing through the bottom wall of the chamber in fluid-tight relationship thereto, said neck defining means for the removal of condensate from the con tainer, steam supply means comprising a pipe extending through said neck and spaced therefrom to further define the condensate removal means as annular, and a drain for said chamber located between its outer wall and said neck; a screen formed as a frustum of a cone and rotatably positioned in the chamber with its largest diameter at the bottom and extending between the outer wall of the chamber and said neck and overlying said drain.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 23,266 Rollins Mar. 15, 1859 138,508 Lee May 6, 1873 271,700 Garstang Feb. 6, 1883 437,910 Theurer Oct. 7, 1890 653,684 Long July 17, 1900 660,499 Fleming Oct. 23, 1900 1,069,829 Thoens et al Aug. 12, 1913 1,276,27 Rossignol Aug. 20, 1918 1,320,080 Mauser Oct. 28, 1919 1,998,122 Dunham Apr. 16, 1935 2,359,041 Keenan Sept. 26, 1944 2,392,893 Williamson Ian. 15, 1946 

1. IN COMBINATION WITH AN EVAPORATOR HAVING AN EVAPORATOR CHAMBER, HEAT TRANSFER MEANS WITHIN THE CHAMBER COMPRISING A CONTAINER PROVIDED WITH A NECK AT THE BOTTOM PASSING THROUGH THE BOTTOM WALL OF THE CHAMBER IN FLUID TIGHT RELATION THERETO, SAID MEANS DEFINING MEANS FOR THE REMOVAL OF CONDENSATE FROM THE CONTAINER, STEAM SUPPLY MEANS EXTENDING THROUGH SAID NECK AND OPENING INTO SAID CONTAINER, AND A DRAIN FOR SAID CHAMBER LOCATED BETWEEN ITS OUTER WALL AND SAID NECK: A SCREEN ROTATABLY POSITIONED IN THE CHAMBER IN THE FORM OF A FRUSTUM OF A CONE EXTENDING BETWEEN SAID OUTER WALL OF THE CHAMBER AND SAID NECK AND OVERLYING SAID DRAIN. 